SRAM XX1 Quarq Power Meter

The 2016 SRAM XX1 Quarq Power Meter is a crankarm-incorporated power meter. Quarq's meters are precise, reporting with less than 1.5% variance. The XX1 meter fits many of SRAM's single-ring drivetrains, compatible with both narrow and standard Q-factor setups of the XX1, X01, and X1 groups. Reporting is via ANT+. Completely self-contained, the built-in accelerometer eliminates the need for a magnet. Available in two arm lengths, with a wide range of chainrings.
A very good power meter for off-road.